1. Field of the Invention
The invention relates to a controller-assisted method and a controller-assisted device for determining the characteristic of a compensation element in a level-control circuit.
2. Related Technology
According to the prior art, the signal level of high-frequency signals, for example, in transmitter output modules, receiver input modules or signal generators, is compensated to an adjustable level-reference value in automatic-gain control (AGC) circuits. EP 0 451 277 B1 discloses an automatic level-control circuit of this kind in a receiver input module. In this context, the amplification and/or attenuation factor of an amplification and/or attenuation element integrated in the signal channel is automatically adjusted via an adjustment signal, which is generated in a controller unit on the basis of the control difference between the level-reference value and the signal level of the high-frequency signal registered via a detector unit at the output of the signal channel.
Non-linearities in the signal channel, for example, in the amplification and/or attenuation element, cause instability in the level-control circuit and impair the dynamics of the level-control circuit.
In the case of DE 36 36 865 A1, an exact inverse adjustment of the transmission characteristic of the attenuation element to the transmission characteristic of the transmitter output module is implemented offline within the framework of an adjustment or calibration procedure by parameterization of the attenuation factor for all level values of the high-frequency signal. Since the course of the transmission characteristic of the transmission output module and, corresponding to this, of the transmission characteristic of the attenuation element, is dependent upon a series of parameters—such as the frequency of the high-frequency signal and the ambient t emperature—a plurality of characteristic courses must be determined for the attenuation element. Once again, within the framework of individual calibration procedures, a plurality of characteristic value pairs must be determined for each individual characteristic. This increases the adjustment cost to a considerable extent before the use of the transmitter, receiver or signal generator.